The cytogenetic results from a series of 113 thyroid hyperplasias and
adenomas are reported; 15 showed clonal karyotypic alterations. In add
ition to a group showing translocations involving 19q13, another subse
t of lesions characterized by polysomies can be found. Based on our ow
n cases belonging to this subset and a review of the cases reported in
the literature, we conclude that the characteristic feature of this g
roup is a sequence that always starts with trisomy 7, but that sometim
es even leads to chromosome numbers in the hypertriploid range. This s
ubset of thyroid tumors may be an example of a more common genetic pat
hway in human solid tumors.